JP6447050B2 - Method for manufacturing power storage device - Google Patents

Description

  The present invention relates to an electricity storage device using a positive electrode containing a nitroxyl compound and a method for producing the same.

  In recent years, portable electronic devices such as notebook computers and mobile phones have become multifunctional, including communication functions, video playback functions, and camera functions. A power storage device used in such portable electronic devices is required to have high energy density, high output characteristics, high safety, and high cycle stability.

  As a high-output power storage device, a power storage device containing a nitroxyl compound in a positive electrode (hereinafter referred to as “organic radical battery”) has been proposed (for example, Patent Document 1). This nitroxyl compound takes an oxoammonium cation partial structure in an oxidized state, takes a nitroxyl radical partial structure in a reduced state, and transfers electrons between the two states, and this reaction is used as an electrode reaction of a positive electrode. . Since this electrode reaction proceeds relatively quickly, a high output battery can be obtained. Moreover, such an organic radical battery is a stable battery that is less likely to run out of heat.

  For example, in the organic radical battery described in Patent Document 2, a negative electrode doped with lithium ions in advance (pre-doped) is used for the purpose of higher output and higher energy density. As a method of pre-doping lithium ions into the negative electrode, in addition to the positive electrode and the negative electrode, an electrode (lithium electrode) composed of a lithium foil and a copper foil (current collector) is provided, and the lithium electrode and the negative electrode are brought into electrochemical contact. It is described that lithium ions are pre-doped on the negative electrode.

  As another pre-doping method, Patent Document 3 describes that, in a lithium ion capacitor, metallic lithium is attached to a negative electrode current collector, and the negative electrode is pre-doped by leaving the battery for a certain time after assembly. ing.

JP 2002-304996 A International Publication No. 2010/140512 JP 2010-232565 A

  When pre-doping is performed by the above-described method, lithium ions are likely to be doped non-uniformly in the negative electrode, so that metallic lithium remains, and there are concerns about problems such as deterioration of battery characteristics and short circuit due to precipitation of lithium dendride.

  An object of the present invention is to provide an electricity storage device with improved output characteristics at low cost.

  A method of manufacturing an electricity storage device according to one embodiment of the present invention takes a nitroxyl cation partial structure represented by the following formula (1) in an oxidized state and a nitroxyl radical partial structure represented by the following formula (2) in a reduced state. A positive electrode containing a nitroxyl compound, a negative electrode containing an active material capable of reversibly inserting and desorbing lithium ions, and an electrolyte solution that exchanges electrons between the oxidized state and the reduced state A method for producing an electricity storage device using the reaction represented by the reaction formula (A) as an electrode reaction of a positive electrode, wherein metallic lithium is bonded to the negative electrode, the electricity storage device is assembled using the negative electrode, and the voltage of the electricity storage device Is 3.0 to 4.0 V, and the negative electrode is pre-doped with lithium ions by holding for 3 days or more after charging.

  An electricity storage device according to another aspect of the present invention is an electricity storage device manufactured by the above manufacturing method.

  According to the embodiment of the present invention, it is possible to provide an electricity storage device with improved output characteristics at low cost.

1 is a perspective view of a laminate type electricity storage device according to an embodiment of the present invention. It is sectional drawing for demonstrating the structure of the lamination type electrical storage device by embodiment of this invention. It is a top view of the negative electrode of the lamination type electrical storage device by embodiment of this invention.

  In the method for manufacturing an electricity storage device according to the embodiment of the present invention, after assembling an electricity storage device having metallic lithium bonded to the negative electrode, the electricity storage device is charged, and after charging is completed, the battery is held in a charged state. Pre-dope with lithium ions. According to this manufacturing method, it is possible to obtain an electricity storage device in which lithium ions are uniformly doped in the negative electrode and output characteristics are improved.

  Hereinafter, a preferred embodiment of the present invention will be described.

  An electricity storage device according to an embodiment of the present invention includes a positive electrode including the nitroxyl compound as a positive electrode active material, a negative electrode, and an electrolytic solution. The negative electrode can contain a material capable of reversibly occluding and releasing lithium ions as a negative electrode active material. A lithium salt can be used as the electrolyte salt, and an aprotic solvent can be used as the organic solvent. Moreover, the film formation additive can be added to the electrolytic solution as necessary.

  The electricity storage device according to the present embodiment can extract electrochemically stored energy in the form of electric power, and can be applied to an electric capacity device such as a primary battery, a secondary battery, a capacitor and a capacitor.

  First, materials used for manufacturing the electrode will be described, and then the structure and manufacturing method of the electricity storage device will be described.

[1] Electrode Material [1-1] Positive Electrode Active Material As the positive electrode active material in the electricity storage device according to the embodiment of the present invention, the nitroxyl cation partial structure (N-oxo-ammonium represented by the formula (1) in the oxidized state is used. A nitroxyl compound having a cation partial structure) and a nitroxyl radical partial structure represented by the formula (2) in a reduced state is used. This nitroxyl compound can perform an oxidation-reduction reaction represented by the reaction formula (A) in which electrons are transferred between these two states. The electricity storage device according to the present embodiment uses this oxidation-reduction reaction as the electrode reaction of the positive electrode.

  The structure of the nitroxyl compound is not particularly limited, but is preferably a nitroxyl polymer compound from the viewpoint of low solubility in an electrolytic solution.

  The nitroxyl polymer compound is preferably a polymer containing a cyclic nitroxyl structure represented by the following formula (Ia) in the side chain in an oxidized state.

(In the formula, R ^{1 to} R ⁴ each independently represents an alkyl group having 1 to 4 carbon atoms, and X represents a divalent group forming a 5- to 7-membered ring, provided that X represents a side chain of the polymer. (By constituting a part, the cyclic nitroxyl structure represented by the formula (Ia) becomes a part of the polymer.)

R ^{1 to} R ⁴ each independently represents an alkyl group having 1 to 4 carbon atoms, preferably an ethyl group or a methyl group, and particularly preferably a methyl group in terms of radical stability.

X is _{specifically, -CH 2 CH 2 -, -} CH 2 CH 2 CH 2 -, - CH 2 CH 2 CH 2 CH 2 -, - CH = CH -, - CH = CHCH 2 -, - CH ═CHCH ₂ CH ₂ —, —CH ₂ CH═CHCH ₂ —, in which non-adjacent —CH ₂ — may be replaced by —O—, —NH— or —S—, -CH = may be replaced by -N =. The hydrogen atom bonded to the atoms constituting the ring may be substituted with an alkyl group, a halogen atom, ═O, an ether group, an ester group, a cyano group, an amide group, or the like.

  Particularly preferred cyclic nitroxyl structures are 2,2,6,6-tetramethylpiperidinoxyl radical (or cation), 2,2,5,5-tetramethylpyrrolidinoxyl radical (or cation), 2,2 , 5,5-tetramethylpyrrolinoxyl radical (cation), 2,2,6,6-tetramethylpiperidinoxyl radical (or cation), 2,2,5,5-tetra A methylpyrrolidinoxyl radical (or cation) is more preferred.

The cyclic nitroxyl structure represented by the formula (Ia) is, as shown in the formula (Ib), a residue X ′ obtained by removing hydrogen from —CH ₂ —, —CH═ or —NH— constituting the ring member in X. Can be attached to the polymer.

Incidentally, R ¹ to R ⁴ of formula (Ib), corresponding to R ¹ to R ⁴ each formula (Ia), X 'is of formula (Ib), constituting the ring members in the X of formula (Ia) This means a residue obtained by removing hydrogen from —CH ₂ —, —CH═ or —NH—.

  The polymer used as the main chain of the nitroxyl polymer compound is not particularly limited as long as the cyclic nitroxyl structure represented by the formula (Ia) can be present in the side chain.

  Examples of the nitroxyl polymer compound include those obtained by adding a group of the formula (Ib) to a normal polymer, or those obtained by substituting some atoms or groups of the polymer with a group of the formula (Ib). The atoms constituting the cyclic structure of the formula (Ib) may be bonded to the polymer (main chain) via an appropriate divalent group in the middle instead of directly. For example, X ′ and the main chain atom of the polymer can be bonded via a divalent group such as an ester bond (—COO—) or an ether bond (—O—).

  As the polymer used as the main chain of the nitroxyl polymer compound, polyalkylene polymers such as polyethylene and polypropylene; poly (meth) acrylic acid; poly (meth) acrylamide and polymethyl are excellent in electrochemical resistance. Poly (meth) acrylamide polymers such as (meth) acrylamide and polydimethyl (meth) acrylamide; poly (meth) acrylate polymers such as polymethyl (meth) acrylate and polyethyl (meth) acrylate; polystyrene, polybromostyrene, polychloro Polystyrene polymers such as styrene and polymethylstyrene are preferred.

  Among such nitroxyl polymer compounds, those having high stability and those represented by any of the following formulas (3) to (7) are preferable.

(In the formula, n is an integer of 1 or more.)

  The nitroxyl polymer compound represented by the formulas (3) to (5) has a 2,2,6,6-tetramethylpiperidinoxyl radical (or cation) in the side chain, and the formulas (6), (7 The nitroxyl polymer compound shown in (2) is a polymer compound having a 2,2,5,5-tetramethylpyrrolidinoxyl radical (or cation) in the side chain. These nitroxyl polymer compounds are compounds having a sterically hindered stable radical in the side chain of the polymer.

  The molecular weight of the nitroxyl polymer compound is preferably 1000 or more, and more preferably 10,000 or more, from the viewpoint of solubility in the electrolytic solution. A higher molecular weight is preferred, but one having an average molecular weight of 5 million or less can be used. This molecular weight is preferably in the range of 1,000 to 5,000,000, and more preferably in the range of 10,000 to 5,000,000, as a weight average molecular weight (in terms of polystyrene) by GPC (gel permeation chromatography).

  The skeleton structure of the nitroxyl polymer compound may be any of a chain, a branch, and a network, and may be a structure crosslinked with a crosslinking agent.

  Moreover, although a nitroxyl polymer compound can be used independently, you may mix and use 2 or more types.

  In addition, a conductive polymer such as polyacetylene, polyphenylene, polyaniline, or polypyrrole, or a carbon material such as activated carbon, graphite, or carbon black may be added to the positive electrode of the electricity storage device according to the present embodiment as a conductive auxiliary agent.

  In view of sufficiently obtaining the effect of adding the nitroxyl polymer compound, the content of the nitroxyl polymer compound in the positive electrode active material is preferably 50% by weight or more, and more preferably 70% by weight or more.

[1-2] Negative Electrode Active Material As the negative electrode active material in the electricity storage device according to the present embodiment, a material capable of reversibly occluding and releasing lithium ions (a material capable of inserting lithium ions during charge and desorbing during discharge) is used. be able to. As such a negative electrode active material, carbon materials such as metal oxides and graphite can be used. The shape of these materials is not particularly limited, and examples thereof include a thin film, a powdered product, a fiber, and a flake. These negative electrode active materials can be used alone or in combination.

[1-3] Conductivity imparting agent When forming the positive electrode and the negative electrode, a conductivity imparting agent may be added for the purpose of reducing impedance. Examples of the conductivity-imparting agent include carbonaceous fine particles such as graphite, carbon black, and acetylene black, carbon fibers such as vapor-grown carbon fibers and carbon nanotubes, and conductive polymers such as polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene. It is done.

[1-4] Binder A binder can also be used when forming the positive electrode and the negative electrode. By using the binder, it is possible to strengthen the connection between the active materials, between the active material and the conductivity imparting agent, and between the active material or the conductivity imparting agent and the current collector. Examples of such a binder include polytetrafluoroethylene (PTFE), polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, Examples thereof include resin binders such as polypropylene, polyethylene, polyimide, partially carboxylated cellulose, and various polyurethanes.

[1-5] Current Collector An electrode material containing a positive electrode active material or a negative electrode active material can be provided on the current collector. As the current collector, a foil, a sheet, a flat plate, or the like made of nickel, aluminum, copper, aluminum alloy, stainless steel, carbon, or the like can be used.

[2] Basic Structure and Manufacturing Method of Power Storage Device FIG. 1 shows a perspective view of an example of a laminated power storage device according to the present embodiment, and FIG. 2 shows a cross-sectional view for explaining the structure. As shown in these drawings, the electricity storage device 108 has a laminated structure including a positive electrode 101, a negative electrode 102 facing the positive electrode, and a separator 105 sandwiched between the positive electrode and the negative electrode. The electrode lead 104 is drawn out to the outside of the exterior film 106. An electrolytic solution is injected into the electricity storage device. Below, the structural member and manufacturing method of an electrical storage device are demonstrated in detail.

[2-1] Positive Electrode The positive electrode 101 includes a positive electrode active material, and further includes a conductivity imparting agent and a binder as necessary, and is formed on one current collector 103.

[2-2] Negative Electrode The negative electrode 102 includes a negative electrode active material, and further includes a conductivity imparting agent and a binder as necessary, and is formed on the other current collector 103.

[2-3] Separator An insulating porous separator 105 is provided between the positive electrode 101 and the negative electrode 102 to insulate and separate them. As the separator 105, a porous resin film made of polyethylene, polypropylene, or the like, a cellulose film, a non-woven cloth, or the like can be used.

[2-4] Electrolytic Solution The electrolytic solution transports the charge carrier between the positive electrode and the negative electrode, and is impregnated in the positive electrode 101, the negative electrode 102, and the separator 105. As the electrolytic solution, a nonaqueous electrolytic solution in which an electrolyte salt is dissolved in an organic solvent can be used. As the solvent for the electrolytic solution, an aprotic organic solvent can be used. If necessary, a film-forming additive can be further added to the electrolytic solution.

Examples of the electrolyte salt include LiPF ₆ , LiClO ₄ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ (hereinafter “LiTFSI”), LiN (C ₂ F ₅ SO ₂ ) ₂ (hereinafter “LiBETI”). ), Li (CF ₃ SO ₂ ) ₃ C, Li (C ₂ F ₅ SO ₂ ) ₃ C, or other ordinary electrolyte materials can be used.

  Examples of the organic solvent include cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; γ-lactones such as γ-butyrolactone; cyclics such as tetrahydrofuran and dioxolane. Ethers; amides such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone and the like. An organic solvent may be used individually by 1 type, or 2 or more types may be mixed and used for it. For example, an organic solvent in which at least one of a cyclic carbonate and a chain carbonate is mixed can be used.

  Examples of the film forming additive include cyclic monosulfonic acid esters such as 1,3-propane sultone and 1,4-butane sultone; cyclic carbonates such as vinylene carbonate; and chain disulfonic acid compounds. As the film forming additive, one kind may be used alone, or two or more kinds may be mixed and used. The content of the film-forming additive in the electrolytic solution is preferably in the range of 0.01% by weight to 10% by weight, and preferably 0.1% by weight or more from the viewpoint of obtaining a more sufficient addition effect. By adding the film forming additive, a high-quality SEI film can be formed, and the battery characteristics can be improved. If the content of the additive is too small, it is difficult to form a high-quality SEI film, and the effect of improving battery characteristics may be reduced. In addition, when the content of the additive is too large, the SEI film is continuously formed, so that the cycle characteristics may be deteriorated. From such a viewpoint, the content of the film forming additive is preferably 10% by weight or less, and more preferably 2% by weight or less.

[2-5] Exterior Film An aluminum laminate film or the like can be used as the exterior film 106. Examples of the exterior body other than the exterior film include a metal case and a resin case. Examples of the outer shape of the electricity storage device include a cylindrical shape, a square shape, a coin shape, and a sheet shape.

[2-6] Example of assembly of electricity storage device Metal lithium 107 was adhered to the surface of the negative electrode 102 (the surface of the active material layer facing the positive electrode) by pressing. At this time, the metal lithium preferably has a surface area A facing the negative electrode surface in a range of 5 to 20% (A / B) of the negative electrode surface area B, and can be provided as a metal lithium film. If the area A of the lithium metal is too large, the lithium metal may remain after the pre-doping treatment. On the other hand, if the area A is too small, lithium ions are not sufficiently pre-doped in the negative electrode, and the effect of improving the battery characteristics due to the pre-doping is obtained. There is a possibility that it cannot be obtained sufficiently. The thickness of the metallic lithium is preferably 20 μm or more from the viewpoint of sufficient pre-doping, more preferably 40 μm or more, and further preferably 60 μm or more. From the viewpoint of preventing the residual lithium metal and adversely affecting the electrode laminate structure, 1000 μm Or less, more preferably 500 μm or less, and even more preferably 300 μm or less.

  The lithium capacity (pre-doping amount) inserted in the negative electrode in advance is preferably 10% or more, more preferably 40% or more of the lithium capacity in which the negative electrode can be inserted and removed during charge / discharge. From the standpoint of suppressing a decrease in stability due to excessive lithium, the negative electrode is preferably not more than 200%, more preferably not more than 120%, and still more preferably not more than 100% of the lithium capacity that can be inserted and removed in charge and discharge. Note that the lithium capacity indicates the capacity of lithium ions. In addition, the lithium capacity in which the negative electrode can be inserted / removed during charge / discharge produces a lithium metal counter electrode, which is charged to a lithium ratio of 0V at a 1 / 40C rate and discharged to a lithium ratio of 1V at a 1 / 40C rate. The measured value is obtained by repeating the cycle 10 times.

  Next, the negative electrode 102 was placed on the exterior film 106, and the electrode 105 was obtained by overlapping the positive electrode 101 with the separator 105 interposed therebetween. The obtained electrode laminate was covered with an exterior film 106 and three sides including the electrode lead portion 104 were heat-sealed. An electrolytic solution was poured into this and vacuum impregnated. After sufficiently impregnating and filling the gap between the electrode and the separator 105 with the electrolytic solution, the remaining one side was thermally fused under reduced pressure, thereby completing the assembly of the laminate-type power storage device 108.

[2-7] Pre-doping treatment Charging is performed as soon as possible after the assembly of the electricity storage device is completed. Charging is preferably performed within 12 hours, more preferably within 6 hours, and even more preferably within 1 hour from the completion of assembly of the electricity storage device. This is because the SEI (solid electrolyte interface) film is formed on the negative electrode surface by charging early after the assembly of the electricity storage device, suppressing the decomposition of the electrolyte solution at the negative electrode-electrolyte interface, and preventing the deterioration of the battery characteristics. Because. In that case, it is preferable to make the voltage of an electrical storage device into the state of 3.0-4.0V by charge, and it is more preferable to set it as the state of 3.4-3.7V. When the voltage is too low, the formation of the SEI film becomes insufficient, and the electrolyte solution may be decomposed at the negative electrode-electrolyte interface during the subsequent holding period. Moreover, when the voltage is too high, the electrolytic solution may be decomposed.

  After charging, the pre-doping treatment can be completed by holding the state of charge obtained by the charging for a sufficient time after the end of charging. The holding time is not particularly limited as long as the pre-doping is sufficiently performed, but from the viewpoint of sufficiently performing the pre-doping, it is preferably 3 days or more, more preferably 1 week or more, and from the viewpoint of efficiency of the production process Therefore, 4 weeks or less is preferable, and 3 weeks or less is more preferable. Here, “holding” means keeping current in a state where no current flows between the positive electrode and the negative electrode of the electricity storage device. If the holding period is too short, metallic lithium remains in the electricity storage device, and the effect of pre-doping may not be sufficiently obtained.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Nitroxyl polymer: Synthesis of PTMA)
Poly (2,2,6,6-tetramethylpiperidinoxyl methacrylate (PTMA), which is a nitroxyl polymer used in this example, was synthesized according to the method described in JP-A-2009-238612. Synthesized according to the following description.

  In a 100 ml eggplant flask equipped with a reflux tube, 20 g (0.089 mol) of 2,2,6,6-tetramethylpiperidine methacrylate monomer was placed and dissolved in 80 ml of dry tetrahydrofuran. Thereto was added 0.29 g (0.00187 mol) of azobisisobutyronitrile (AIBN) (monomer / AIBN = 50/1), and the mixture was stirred at 75 to 80 ° C. in an argon atmosphere. After reacting for 6 hours, it was allowed to cool to room temperature. The polymer was precipitated in hexane, separated by filtration, and dried under reduced pressure to obtain poly (2,2,6,6-tetramethylpiperidine methacrylate).

  Next, 10 g of the obtained poly (2,2,6,6-tetramethylpiperidine methacrylate) was dissolved in 100 ml of dry-treated dichloromethane. To this, 100 ml of a dichloromethane solution of 15.2 g (0.088 mol) of m-chloroperbenzoic acid was added dropwise over 1 hour with stirring at room temperature. After further stirring for 6 hours, the precipitated m-chlorobenzoic acid was removed by filtration, and the filtrate was washed with an aqueous sodium carbonate solution and water, and then dichloromethane was distilled off. The remaining solid was pulverized, and the resulting powder was washed with diethyl carbonate (DEC) and dried under reduced pressure to obtain poly (2,2,6,6-tetramethylpiperidinoxyl methacrylate) (PTMA). Obtained. The weight average molecular weight by GPC was 89000.

(Preparation of negative electrode)
13.5 g of graphite powder (average particle size 6 μm), 1.35 g of polyvinylidene fluoride, 0.15 g of carbon black, and 30 g of N-methylpyrrolidone were mixed and stirred with a homogenizer to prepare a uniform slurry.

  This slurry was applied on a copper mesh (thickness 30 μm) as a current collector, and then dried at 120 ° C. for 5 minutes. Furthermore, the thickness was adjusted with a roll press. This was cut out into a 23 × 25 mm rectangle, and a nickel electrode lead was ultrasonically bonded. The thickness of the obtained negative electrode (active material layer) was 50 to 60 μm.

(Preparation of positive electrode)
PTMA 2.1 g as the positive electrode active material, carbon material 0.63 g as the conductivity-imparting agent, carboxymethylcellulose (CMC) 0.24 g and polytetrafluoroethylene (PTFE) 0.03 g as the binder, and 15 ml of water were mixed. The mixture was stirred with a generator to prepare a uniform slurry.

  This slurry was applied on an aluminum foil (thickness 40 μm) as a current collector, and then dried at 80 ° C. for 5 minutes. Furthermore, the thickness was adjusted with a roll press. This was cut into a 22 × 24 mm rectangle, and an aluminum electrode lead was ultrasonically bonded. The thickness of the positive electrode (active material layer) obtained was 140 to 150 μm.

Example 1
Metal lithium with a thickness of 100 μm is cut into a circle with a diameter of 8.5 mm (the area of the metal lithium facing the negative electrode corresponds to 10% of the area of the negative electrode surface) and bonded to the negative electrode surface (graphite surface side) by pressing. It was.

As shown in FIG. 2, a polypropylene porous film separator is sandwiched between the negative electrode and the positive electrode to form an electrode laminate, the electrode laminate is covered with an aluminum laminate film, and the three sides including the electrode lead portions are heated. Fused. A mixed electrolyte solution of ethylene carbonate / dimethyl carbonate = 40/60 (v / v) containing LiPF ₆ (supporting salt) at a concentration of 1 mol / L was poured into the electrode and thoroughly impregnated in the electrode. The assembly of the laminate-type electricity storage device was completed by thermally fusing the remaining one side under reduced pressure.

  The battery was charged at 10 mA for 10 minutes within 1 hour from the completion of the assembly of the electricity storage device. The voltage after charging was 3.42V. Thereafter, the pre-doping treatment was completed by holding (leaving) for 2 weeks.

(Example 2)
An electricity storage device was assembled in the same manner as in Example 1. The battery was charged at 10 mA for 20 minutes within 1 hour after the assembly of the electricity storage device was completed. The voltage after charging was 3.50V. Thereafter, the pre-doping treatment was completed by holding (leaving) for 2 weeks.

Example 3
An electricity storage device was assembled in the same manner as in Example 1. The battery was charged at 10 mA for 30 minutes within one hour after the assembly of the electricity storage device was completed. The voltage after charging was 3.55V. Thereafter, the pre-doping treatment was completed by holding (leaving) for 2 weeks.

(Example 4)
Metal lithium having a thickness of 100 μm was cut into a circle with a diameter of 7.0 mm (the surface of the metal lithium facing the negative electrode corresponds to 8% of the area of the negative electrode surface) and adhered to the negative electrode surface (graphite surface side) by pressing. .

As shown in FIG. 2, a polypropylene porous film separator is sandwiched between the negative electrode and the positive electrode to form an electrode laminate, the electrode laminate is covered with an aluminum laminate film, and the three sides including the electrode lead portions are heated. Fused. A mixed electrolyte of ethylene carbonate / dimethyl carbonate = 40/60 (v / v) containing LiPF ₆ (supporting salt) with a concentration of 1 mol / L and 1% by weight of vinylene carbonate (additive for film formation) was injected into this. The electrode was well impregnated. The assembly of the laminate-type electricity storage device was completed by thermally fusing the remaining one side under reduced pressure.

  The battery was charged at 10 mA for 10 minutes within 1 hour from the completion of the assembly of the electricity storage device. The voltage after charging was 3.51V. Thereafter, the pre-doping treatment was completed by holding (leaving) for 2 weeks.

(Comparative Example 1)
An electricity storage device was assembled in the same manner as in Example 1. After the assembly of the electricity storage device was completed, charging was not performed (the voltage was 2.41 V), and the pre-doping treatment was completed by holding (leaving) for 2 weeks.

(Comparative Example 2)
An electricity storage device was assembled in the same manner as in Example 1. The battery was charged at 10 mA for 30 minutes within 1 hour from the assembly of the electricity storage device. The voltage after charging was 3.55V. Thereafter, the pre-doping treatment was completed by holding (leaving) for one day.

(Comparative Example 3)
Except that 100μm thick metallic lithium is cut out into a circle with a diameter of 14mm (the surface of the metallic lithium facing the negative electrode is equivalent to 30% of the negative electrode surface) and bonded to the negative electrode surface (graphite surface side) by pressing Was assembled in the same manner as in Example 1. The battery was charged at 10 mA for 30 minutes within 1 hour from the assembly of the electricity storage device. The voltage after charging was 3.57V. Thereafter, the pre-doping treatment was completed by holding (leaving) for one day.

(Comparative Example 4)
An electricity storage device was assembled in the same manner as in Comparative Example 3. The battery was charged at 10 mA for 30 minutes within 1 hour from the assembly of the electricity storage device. The voltage after charging was 3.51V. Thereafter, the pre-doping treatment was completed by holding (leaving) for two weeks.

(Remaining metallic lithium)
The power storage devices of Examples 1, 2, 3, and 4 and Comparative Examples 1, 2, 3, and 4 were disassembled, and it was confirmed whether metallic lithium remained in the power storage device. Table 1 shows the results. In Examples 1, 2, 3, 4 and Comparative Example 1, no metallic lithium remained, but in Comparative Examples 2, 3, and 4, the remaining metallic lithium was confirmed.

(Output measurement and results)
The power storage devices of Examples 1, 2, 3, 4 and Comparative Example 1 were charged at 20 ° C. with a constant current of 0.5 mA until the voltage reached 4 V, and then discharged at 20 ° C. and 10 mA for 1 second. did. Thereafter, the battery was charged at 20 ° C. with a constant current of 0.5 mA until the voltage reached 4 V, and then discharged at 20 mA at 20 mA for 1 second. This charging / discharging was repeated while changing the discharge current to 30, 40, ..., 1000 mA. The output was obtained by multiplying the discharge end voltage and the measured current. The largest output among the outputs at each discharge current was defined as the maximum output.

Table 2 shows the maximum output results. The maximum outputs of Example 1, Example 2, Example 3, Example 4, and Comparative Example 1 are 293 mW / cm ² , 315 mW / cm ² , 324 mW / cm ² , 352 mW / cm ² , and 246 mW / cm ² , respectively. there were. Thus, the output characteristics of Example 1, Example 2, Example 3, and Example 4 were higher than those of Comparative Example 1. From this result, it was possible to improve the output characteristics by charging after assembly of the electricity storage device. Further, Example 4 had the highest output, and the output characteristics could be improved by using the film forming additive.

  According to the embodiment of the present invention, a high-output power storage device can be provided at a low manufacturing cost. Therefore, the power storage device obtained according to the embodiment of the present invention is a storage power source for driving or auxiliary such as an electric vehicle and a hybrid electric vehicle, a power source for various portable electronic devices, and various energy storages such as solar energy and wind power generation. It can be applied to a storage power source of a device or a household electric appliance.

DESCRIPTION OF SYMBOLS 101 Positive electrode 102 Negative electrode 103 Current collector 104 Electrode lead 105 Separator 106 Exterior film 107 Metal lithium 108 Laminate type electricity storage device

Claims (11)

A positive electrode containing a nitroxyl compound having a nitroxyl cation partial structure represented by the following formula (1) in an oxidized state and a nitroxyl radical partial structure represented by the following formula (2) in a reduced state; A negative electrode containing an active material that can be inserted / removed, an electrolyte, and a reaction represented by the following reaction formula (A) that exchanges electrons between the oxidized state and the reduced state is performed as a positive electrode A method for producing an electricity storage device used as a reaction,
Lithium metal is bonded to the negative electrode, an electric storage device is assembled using the negative electrode, charged so that the voltage of the electric storage device is 3.0 to 4.0 V, and held for 3 days or more and 4 weeks or less after charging. A step of pre-doping lithium ions to the negative electrode ,
The ratio (A / B) of the area A of the surface of the metallic lithium facing the negative electrode surface to the area B of the negative electrode surface is in the range of 5 to 20%, and the thickness of the metallic lithium is in the range of 20 μm to 300 μm. A method for manufacturing an electricity storage device according to claim 1.
Wherein the area A of the surface opposite the surface of the negative electrode of metallic lithium, the ratio (A / B) with respect to the area B of the negative electrode surface, 5 is the 10% range, a manufacturing method of an electric storage device of claim 1, wherein . The manufacturing method of the electrical storage device of Claim 1 which has the thickness of the said metal lithium in the range of 20 micrometers- 100 micrometers. The thickness of the metallic lithium is in the range of 20 μm to 100 μm, and the ratio (A / B) of the area A of the surface of the metallic lithium facing the negative electrode surface to the area B of the negative electrode surface is 5 to 10%. The manufacturing method of the electrical storage device of Claim 1 which exists in a range. Holding more than one week after the charging method of an electric storage device according to claim 1. The method for manufacturing an electricity storage device according to any one of claims 2 to 4, wherein the battery is held for one week or more after the charging. The manufacturing method of the electrical storage device as described in any one of Claim 1 to 6 hold | maintained for 3 weeks or less after the said charge. The method for manufacturing an electricity storage device according to any one of claims 1 to 7, wherein in the charging, the voltage of the electricity storage device is in a range of 3.4 to 3.7V. The manufacturing method of the electrical storage device as described in any one of Claim 1 to 8 which performs the said charge within 12 hours after completing the assembly of the said electrical storage device. The method for manufacturing an electricity storage device according to any one of claims 1 to 9 , wherein the nitroxyl compound is a polymer including a cyclic nitroxyl structure represented by the general formula (Ia) in a side chain in an oxidized state.

(In the formula, R ^{1 to} R ⁴ each independently represents an alkyl group having 1 to 4 carbon atoms, and X represents a divalent group forming a 5- to 7-membered ring, provided that X represents a side chain of the polymer. (By constituting a part, the cyclic nitroxyl structure represented by the formula (Ia) becomes a part of the polymer.) The electrolytic solution is an electrolytic solution containing a lithium salt, an aprotic solvent, and a film forming additive, and the content of the film forming additive is in the range of 0.01% by weight to 10% by weight. The manufacturing method of the electrical storage device as described in any one of Claims 1-10 .